Alcohol abuse and alcoholism are widespread public health problems that are associated with debilitating medical, social, and psychological consequences. The abuse of alcohol is controlled by multiple effects of the drug, including its subjective and reinforcing effects and its capacity to trigger relapse. Preclinical methods have been developed to assess the contribution of these controlling factors and their neurobiological underpinnings, and to provide empirically-based models for evaluating potential treatment strategies. The purpose of this renewal application is to investigate the role of a2/3GABAA and a5GABAA receptor mechanisms in nonhuman primate models of the abuse-related effects of alcohol. We will systematically investigate the contribution of a2/3GABAA receptor mechanisms (Specific Aim 1) to the behavioral effects of alcohol by determining how receptor selective agonists and antagonists modulate: 1) the discriminative stimulus effects of alcohol in rhesus monkeys trained to discriminate intragastrically-administered alcohol from vehicle, 2) oral self-administration of alcohol in rhesus monkeys, and 3) reinstatement of alcohol seeking in rhesus monkeys whose oral self-administration has been extinguished and subsequently reinstated by alcohol priming. Understanding the neuropharmacological mechanisms underlying the addictive effects of alcohol is an important initial step in the development of candidate pharmacotherapies for the treatment of alcohol abuse and dependence. Additionally, we will continue to evaluate novel a5GABAA receptor inverse agonists with different chemical structures and potentially more suitable behavioral profiles in these same behavioral models (Specific Aim 2). Results from these studies should support the notion of the a5GABAA receptor as a relevant target for the pharmacological management of alcohol use disorders. The degree to which the effects of a2/3GABAA and a5GABAA receptor ligands selectively modify alcohol-controlled behavior (Specific Aim 3) will be evaluated in rhesus monkeys that self-administer a sucrose solution instead of alcohol and in concurrent observational studies of the effects these ligands, alone or combined with alcohol, on unconditioned motor behavior. The ability of selected a2/3GABAA and a5GABAA ligands to blunt the discriminative stimulus effects of alcohol, reduce alcohol self-administration and attenuate priming-induced reinstatement of alcohol seeking at doses that do not produce a generalized disruption of behavior or debilitating side effects may be predictive of potential therapeutic utility. Integration of results from these three specific aims will provide needed information about specific GABAA mechanisms that may underlie the addictive effects of alcohol and will aid identification of receptor targets for the pharmacological management of alcohol abuse and relapse.